Yeah, probably to stay practical the size would be more toward the A2's....Was thinking of doing pretty much what your showing only build the drivers into an aluminum body that is light but kinda cool looking (I can buy lots of cheapy stuff that works but knurled aluminum would be cool).
I mean, it might be more practical to go buy one of the many bluetooth options but sounded kinda neat to make an enclosure that's kind of creative (like you showed you put your A5s in) but really small.
After a while in these hotel rooms you kinda try and make it a little more like home. We kinda setup shop in them. But, obviously travelling overseas (especially with the gear we take) you want to stay really small.
Was almost thinking of the size of an A2 but thinner and longer. (but around the same volume).